#top{
    width: 780px;
    height: 188px;
    float: left;
    margin-bottom: 2px;
}
#banner{
    width: 780px;
    height: 150px;
    background: url(../img/banner.jpg) no-repeat;
    float: left;
}
#nav{width: 780px;
    height: 33px;
  
}
#nav ul{
    list-style: none;
}
#nav li{
    float: left;
    width: 78px;
    height: 33px;
    text-align: center;
    line-height: 33px;
    background: url(../img/button1.jpg) ;
}
#nav a{
    color: #256498;
}
#nav li:hover{
    position: relative;
    right: 1px;
    bottom: 1px;
    background: url(../img/button1_bg.jpg);
}